The bill bans any device for a pistol, rifle or shotgun that increases the rate of fire and repeated activation of the trigger.

Denver is just the second city in the country to pass such a ban.

The state legislature is considering similar action. Hearings are underway at the Capitol to implement a statewide ban on bump stocks.

"Having seen what's happened in Las Vegas, being concerned in Colorado, I think it's reasonable we outlaw the purchase and sale of bump stocks," said State Sen. Michael Merrifield, D-Colorado Springs.

But its chances of passing in the State Senate, which is controlled by Republicans, is slim.

"It's just one more example of government overreach, meaning well and trying to address some of the issues, but the result is we make life harder for law-abiding citizens," said State Sen. Owen Hill, R-Colorado Springs. "And we don't do anything to solve the crime, which is bad people with guns.

"Even is we pass something here in Colorado, there are 49 other states where you can buy it online. The internet has upended all of this. It's well-meaning, but at the end of the day, it takes away the Second Amendment rights of law-abiding citizens and doesn't cut down on gun violence."

Fines under the new Denver law could be as much as $1,000 and up to 180 days in jail.